Integrated stratigraphy and palaeoenvironment of the Berriasian peri-reefal limestones at Štramberk (Outer Western Carpathians, Czech Republic)

Abstract

A high-resolution multidisciplinary study of two profiles in the Kotouc Quarry at Stramberk was carried out to define the age and palaeoenvironmental setting of the peri-reefal Stramberk Limestone. Calpionellids of the Alpina and Ferasini subzones of the standard Calpionella Zone confirm an early Berriasian age for both studied sequences. The presence of the calcareous nannofossils Nannoconus kamptneri minor and ?Speetonia colligate supports this stratigraphic interpretation. An ammonite assemblage with Pseudosubplanites grandis was found corresponding to the upper part of the lower Berriasian (Grandis Subzone). Foraminiferan assemblages contain several taxa previously reported from the Valanginian. Magnetostratigraphy verifies that the studied sections span the magnetozones M18r to M18n. Rock magnetic measurements indicate magnetite as the carrier of characteristic remanent magnetization. A palaeolatitude suggested location at 36 degrees N. Microfacies indicate palaeoenvironments of slope (FZ 4), platform margin reefs, sand shoals (FZ 5, FZ 6) and possibly patch-reefs in the inner platform (FZ 7). The presence of calpionellids and the polychaete Terebella lapilloides suggests deposition within the deeper parts of the outer ramp of a platform slope, with redeposited clasts derived from nearby reef slopes and/or talus. This research contributes to the Berriasian Working Group's efforts to define the Tithonian-Berriasian boundary.